Manufacture of paper bags



28, 1940- K. ROHRBACHER 2,202,431

MANUFACTURE OF PAPER BAGS Filed July 13, 1937 3 Sheets-Sheet 1 7 //7 ventor: I

y 1940- K. ROHRBACHER 2, 02,431

MANUFACTURE OF PAPER BAGS Filed July 13, ,1937 3 Sheets-Sheet 2 In yen tor:

K. ROHRBACHER MANUFACTURE OF PAPER BAGS May 28, 1940.

Filed July 13, 1937 3 Sheets-Sheet 5 Fwy v Patented May 28, 1940 MANUFACTURE OF PAPER BAGS Karl Rohrbacher, Berlin, Germany Application July 13, 1937, Serial No. 153,426 In Germany July 18, 1936 14 Claims.

This invention relates to a method of producing block bottoms on flattened paper tubes while being fed in a direction transversely to their length, that is with the open edges parallel to the direction of feed, and to a device for carrying out this method.

The invention consists in opening the leading part of the flattened tube atone end, forcing the sides of the leading part outwardly transversely to the plane of the flattened tube to form a pocket having a side in the form of a rightangled isoceles triangle, rolling the pocket in the direction of feed in a plane at right angles to the plane of the flattened tube, so as toflatten the pocket, and continuing the rolling to turn up the ends of the sides 'of 'theflattened tube, thereby forming and flattening a corresponding pocket at the rear part of the tube.

Preferably, during the rolling operation, the pockets and the upturned ends of the tube between the pockets are creased along lines parallel to the plane of the flattened tube and intermediately of said plane and the edges of the upturned ends, so that,'for completing the bag bottom, the two end portions extending outwardly from these creases only require to be bent over each by 180 and stuck together.

In the manufacture of so-called valved bags,

the continuously fed tube lengths are operated on at both open edges simultaneously in the same manner, the only difference being that at one side provision has to be made in a known manner for the forming of the valve opening.

The inventionis illustrated diagrammatically by way of example in the accompanying drawings, in which Figs. 1 to '5. show a side view (that is at right angles to the direction of feed) in various operative positions.

Fig. 6a shows a detail,

Figs. 6 and '7 are front views of Figs; 1 to 5, Fig. 6 corresponding to Fig. 3 and Fig. '7 to Fig.4. In order to simplify the illustration some parts are omitted in Figs. 6 and 7.

Fig. 8 is a plan view of Figs. 6 and '7, the position of the parts corresponding to that of Fig. 7.

Fig. 9 is a side elevation of a machine with the front side of the machine bed removed to show the driving mechanism for the various Figure 11 is a perspective view showing one or the grippers v1, in.

The paper tube p which is held down on a feed angle with the direction of feed of the tube,

table in a. known manner and is conveyed in the flattened state horizontally in, a direction at right angles to its length first passes between two rollers '1', m (Fig. 1), which engage the tube at such a distance from the open edge of the 5 tube that a sufiicient marginal strip 111 of the tube p for forming the block bottom projects outwards (Fig. 6).

For limiting the bottom-forming operations to the marginal strip 111 of the tube 11 two rails f 10 and i which are parallel to one another serve in a known manner, these rails being shown only in Figs. 6a and 10 and being omitted in all the. other figures for the sake of clearness. The lower rail may be formed. by the feed table 15 itself, Whilst the upper rail 2' is made adjustable in the usual way so as to enable its distance from the lower rail i to be adapted to the thickness of the blanks to be operated on.

As soon as the paper tube p'has passed. between the rollers 1'1, 1'2, the leading part of the tube end is opened by suction members s1, 82' (Fig. 2) in such a manner that the side walls of the free marginal part 111, which have hith=- erto lain flat on one another, are bent apart in opposite directions. As the suction members s1, 82 are mounted on the same shafts w, 1122 as the rollers 11, 1'2 and revolve at the same speed as the latter, the suction members s1, s2 will detach themselves again from the marginal part a of the tube, when they have turned through a certain angle (Fig. 3).

Previously to the suction members s1, s2 detaching themselves, however, two preliminary grippers v1, 02 enter the tube part in which has been slightly opened by the suction members $1, $2 (Fig. 2), which grippers turn in opposite directions in a plane which is both perpendicular to the directional feed of the papertube p and perpendicular to-the plane of rotation of the suction members s1, s2 (and of the rollers 1'1, m). The preliminary grippers v1, 122 continue the open ing of the tube at its marginal part 111 to an extent which is limited by the nip of the rollers r1, 12 (Fig. 3), whereupon two main grippers 71.1, In act on the tube part n (Figs. 3 and 4 and Figs. 6 to 8).

The two main grippers hi, 712- of sickle-like form are mounted on shafts e1, e: which form an preferably an angle of 45. The speed of the main grippers hl, hz, which also turn in opposite directions, is made such that the velocity component acting in the direction of feed of the tube has at least' the same value as the speed of 55 feed itself. The main grippers hi, hz during their rotation form at the forward edge of the free part 111 of the tube a pocket t1 having a wall, which lies in a plane perpendicular to the plane of feed (Fig. 4).

As soon as the main grippers hl, ha have drawn the forward pocket t1 so far apart that it has the form of a right-angled isosceles triangle, this pocket i1 is transferred by the main grippers hl, hz to a pair of rollers .a1, 112, which roll out and flatten the pocket ti produced by'the main grippers hl, hz (Fig. 8). These rollers a1, (12 are arranged so as to meet in the plane of the pocket 751 with their axes 04, as perpendicularto the direction of feed.

At the inside of the pocket t1 the roller (12 is in two parts, as the horizontal main part 11 of the tube has to pass through here. The externally situated roller or has in the middle a recess as, in order that the pocket 261 shall not be unnecessarily weakened at its point by being too sharply rolled out. The same applies to the second pocket 122 which is subsequently produced at the rear edge of the marginal part in.

The main grippers in, hz arranged on the inclined shafts e1, e2, operate in such a manner that the pocket ii is transferred to the rollers a1, az at the moment at which its production by the main grippers hi, h2 is completed, so that the pocket ii is never left to itself.

On the paper tube 10 continuing to advance, the second pocket i2 is formed at the rear edge of the free marginal part m, as soon as the rollers a1, an approach the end of the tube owing to the two side walls of the free marginal part 1 being bent over by in opposite directions during the passage thereof between the rollers (11, (7.2, so that at the rear edge or the marginal part 201 a pocket 152 of exactly the same shape as the forward pocket t1, that is to say having the form-of a right-angled isosceles triangle, must be formed positively.

The rollers r1, r2 may at the same time serve for forming a crease b1 (Fig. 6) between the free marginal part 111 and the inwardly lying main part p of the tube. Similarly the rollers (11, (12 may form a crease b2, b; in the middle of the vertically extending side walls (Fig. 5), so that, after they have passed through between the rollers a1, 112, it is only'necessary, for forming the block bottom, to bend over the outer parts 112, p3 of the side walls through to one another.

The ribs or grooves provided on the pair of rollers (11, oz for forming the creases b2, b3 are preferably adjustable, so as to enable the creases b2, D3 to be easily displaced, when the width of the free marginal part 171, that is to say the width of the bottom of the bag, is altered. The suction member s, and the preliminary grippers v1, 02

.should also be coupled with one another in such a manner that the relation between the two parts is always maintained, so that, when the width of the bag bottom is to be altered, the suction members s1, s2 and the preliminary grippers v1, oz can also always be pointly adjusted.

The arrangement of the shafts e1, ez for the main grippers hi, ha, such that they form an angle of 45 with the direction of feed of the paper tube 17 and that the point of intersection of their axes lies in a plane which passes through the axes a4,- aa of the two vertically arranged rollers (11, 112, provides the advantage, that the grippers hi, hz will be easily adjustable through being simply displaced on their shafts to the marginal parts n of different width of the paper tube and therefore to bag bottoms of different widths.

In order, after the forming of the forward pocket ii, to assist the proper stretching of the free side walls of the marginal part 291 in the vertical position, counter pressure cylinders or rollers h may coact with the main grippers hi, ha, which rollers are so arranged behind the side walls which have been bent over by 90 that their axes lie parallel to the corresponding axes of the main grippers hi, hz. This arrangement prevents the stresses set up, during the forming of the forward pocket ii, in the part of the marginal portion p1 lying behind it, causing the blank to enter between the rollers (11, a: on the skew or in a distorted state, which might give rise to folds in the side walls and to the rear pocket t2 being rolled out askew.

What I claim is:

1. In a method of producing paper bags with block bottoms, the steps consisting in feeding a flattened paper tube in a direction transversely to its length, engaging the sides of the leading part of the flattened tube at one end and forcing the sides of said leading part outwardly transversely to the plane of the flattened tube, so as to form a pocket having a side in the form of a 1 right-angled isosceles triangle, rolling said pocket in the direction of feed in a plane at right angles to the plane of the flattened tube, so as to flatten the pocket, and continuing the rolling to turn up the ends of the sides of the flattened tube and to form and flatten a. corresponding pocket at the trailing part of the tube.

2. In a method of producing paper bags with block bottoms, the combination of the steps as set forth in claim 1 with the additional step consisting in creasing the pockets and the upturned ends of the tube between the pockets along lines parallel to the plane of theflattened tube and intermediately of said plane and the edges of the upturned ends.

3. For producing paper bags with block bottoms, the combination of feeding means for feeding a flattened paper tube in a direction transversely to its length, means for opening the leading part of the flattened tube at one end, a pair of grippers arranged at an inclination to the direction of feed of the tube and rotatable in opposite directions, so as to engage and force the sides of the tube apart and form a pocket at said leading part having a side in the form of a rightangled isosceles triangle, and rollers having their axes extending at right angles to the plane of the flattened tube and arranged to flatten the pocket formed by the grippers, to bend up the sides of the flattened tube adjacent the pocket at right angles to the plane of the flattened tube and form and flatten a corresponding pocket at the rear part of the tube end.

4. For producing paper bags with block bottoms, the combination of feeding means for feeding a. flattened paper tube in a direction transversely to its length, means for opening the leading part of the flattened tube at one end, a pair of grippers of substantially sickle-shape arranged at an inclination to the direction of feed of the tube and rotatable in opposite directions, so as to engage and force the sides of the tube apart and form a pocket at said leading part having a side in the form of a right-angled isosceles triangle, and rollers having their axes extending atright angles to the plane of the flattened tube and arranged to flatten the pocket formed by the grippers, to bend up the sides of a corresponding pocket at of feed of the part of the flattened tube at theflattened tube adjacent the pocket at right angles to the plane of the flattened tube and form and flatten a corresponding pocket at the rear part of the tube end.

5. For producing paper bags with block bottoms, the combination of feeding means for feedand force the sides of the tube apart and form a pocket at said leading part having a side in the form of a right-angled isosceles triangle, and rollers having their axes extending. in a vertical plane at right anglesto the direction of'feed and to the plane of the flattened tube and arranged to flatten the pocket formed by the grippers, to bend up thesides of the flattened tube adjacent the pocket at right angles to'the plane of the flattened tube and form and flatten a corresponding pocket ,at the rear part of: the tube end, the axes of the grippers being arranged so as to intersect the vertical plane containing the axes of the rollers; so as to enable the grippers'to be adjusted to form pockets of difierent widthsimply by displacing them axially.

6. For producing paper bags with block bottoms, the combination of feeding means for feeding a flattened paper tube in a direction transversely to its length, a pair of suction members arranged to'draw apart and open the leading one end, a pair of grippers arranged at an inclination to the direction of feed and rotatable in opposite directions, so as to engage and force thesides of 'the tube apart and form a pocket at said leading part having a side in the form of a right-angled isosceles triangle, and rollers having their axes extending in a plane at right angles to the'direction of feed and to the plane of the flattened tube and arranged to flatten the pocket formed by the grippers, to bend up the sides' of the flattened tube adjacent the pocket at right angles to the plane of the flattened tube and form and flatten the rear part of the tube end. I

'7. For producing paper bags with block bottoms, the combination of a pair of feed rollers arranged to engage a flattened paper tube at a point spaced from one end thereof and to feed the tube in'a direction transversely to 'its length, a pair of suction members arranged to rotate in opposite directions coaxially and in unison with said-feed rollers for opening the leading part of the flattened tube at one end, a pair of grippers arranged at an inclination tothe direction tube androtatable in opposite directions, so as to engage and force the sides of the tube apart and form a pocket at said leading part having a sidein the form of a rightangled isosceles triangle, and rollers having their axes extending in a plane at right angles to the direction of feed and to the plane of the flattened tube and arranged 'to flatten the pocket formed by the'grippers, to bend up the 'sides of the flattened tube adjacent the pocketat right angles to the plane of the flattened tube and form and flatten a corresponding pocket at the rear part of the tube end. v

8. For producing paper bags with block bottoms, the combination of feeding means for feeding a flattened paper tube in a direction transversely. to its length, a pair of suction members arranged to draw apart and open the leading part of the flattened tube at one end, a pair of preliminary grippers arranged to engage the opened part 01 the flattened tube and continue the opening movement initiated by'the suction members during the continued feed of the tube, a pair of main grippers arranged at aninclination to the direction of feed and rotatable in opposite directions, so as to engage and force the opened sides of the tube apart to form-a pocket at said leading part having a side in the form of a right-angled isosceles triangle, and rollers having their axes extending at right angles to the direction of feed'and' to the 'plane of the flattened tube and arranged to flatten the pocket formed by said main grippers, to bend up the sides of the flattened tube adjacent the pocket at right angles to the plane of the flattened tube and form and flatten a corresponding pocket at the rear part of the tube end.

9. For producing paper bags with block bottoms, the combination of feeding means for feeding a flattened paper tube ina direction transversely to its length, a pair of suction members arranged to draw apart and open the leading part of the flattened tube at one end, a pair of preliminary grippers arranged for rotation in opposite directions in a plane perpendicular to the direction of feed about axes parallel to the direction of feed, so as ,to engage the opened part of the flattened tube and continue the'operzing movement initiated by the suction members dur-- mg the continued feed of the tube, a pair ofmain grippers arranged at an inclination to-the direction of feed and rotatable in opposite directions, so as to engageand force the opened sides of the tube apart to form a pocket at said leading part having a side in the form of a rightangled isosceles triangle, and rollers having their 'axes extending at right angles to the direction ing a flattened paper tube in a direction trans- ,versely to its length, a pair of suction members arranged to draw apart and open the leading part of the flattened tube at one end, a .pair of preposite directions in a plane perpendicular to the direction of feed about axes parallel to the direction of feed, so as to engage the opened partof the flattened tube and continue the opening movement initiated by the suction members during the continued feed of the tube, said suction members and preliminary grippers being displace'able in unison in a direction transversely to the direction of feed, so as to enable the suction members and preliminary grippers -to be adjusted jointly for varying the width of the bag bottom, a pair of main grippers arranged at an inclination to the direction of feed and rotatable in opposite directions, so as to engage and force form of a right-angled isosceles triang1e,and rollers having their ax'es extending at right angles to the direction of feed and to the plane of the flattened tube and arranged to flatten the pocket formed by said main grippers, to bend up the liminary grippers arranged for rotation in op-v posite directions, so as to engage and force the v sides of the tube apart and form a pocket at said leading part having a side in the form of a rightangled isosceles triangle, and rollers having their 'axes extending at right angles to the plane of the flattened tube and arranged to flatten the pocket formed by the grippers, to bend up the sides of the flattened tube adjacent the pocket at right angles to the plane of the flattened tube and form and flatten a corresponding pocket at the rear part of the tube end, the said rollers comprising a pair to engage one side of the pock- 'ets and spaced endwise from one another to form a gap for the reception or the main part of the flattened tube. j

12. For producing paper bags with block bottoms, the combination of feeding means for feeding a flattened paper tube in a directiontransversely to its length,means for opening the leading part of the flattened tube atone end, a'pair of grippers arranged at an inclination to the direction of feed of the tube and rotatable in opposite directions, so as to engage and iorce the sides of the tube apart and form a pocket at said leading part having a side'in the form of a rightangled isosceles triangle; and rollers having their axes extending at right angles to the plane or the flattened tube and arranged to flatten the pocket formed by the grippers, to bend up the sides of the flattened tube adjacent the pocket at right angles to the plane of the flattened tube and form and flatten a corresponding pocket at the rear part of the tube end, the said rollers having coacting ribs and depressions arranged to crease the pockets and the upturned ends of the tube between the pockets along lines parallel to the plane of the flattened tube and intermediately of said plane and the edges of the upturned ends.

13. For producing paper bags with block bottoms, the combination of feeding means for feeding a flattened paper tube in a direction transversely to its length, means for opening the leading part of the flattened tube at one end, a pair of grippers arranged at an inclination to the direction of feed of the tube and rotatable in opposite directions, so as to engage and force the sides of the tube apart and form a pocket at said leading part having a side in the form of a rightangled isosceles triangle, and rollers having their axes extending at right angles to the plane of the flattened tube and arranged to flatten the pocket formed by the grippers, to bend up the sides of the flattened tube adjacent the pocket at right angles tothe plane of the flattened tube and form and flatten a corresponding pocket at the rear part of the tube end, the said rollers comprising a roller for engaging the side of the pockets remote from the main part of the flattened tube, said roller having a depression midway between its ends for relieving the pressure acting on the portion of said side in proximity to the plane of the'flattened tube.

14. For producing paper bags with'block bottoms, the combination as set forth inclaim 3 with counter-pressure rollers arranged with their axes parallel to the axes of the respective grippers so as to engage behind the side walls oi the pocket formed by the grippers in the flattened tube.

KARL ROI IRBACI IER. 

